Method for producing a ventilation duct system

Abstract: A kit for producing a connector (24) for fluid pipe elements comprises loose sleeve couplings (1, 2) and at least one flat blank (3, 4) which has been given such a shape and such dimensions that, after forming thereof and interconnecting its opposite ends, it is connectable with the sleeve couplings (1, 2) by means of a peripheral joint, thereby forming an intermediate segment (3', 4'). The sleeve couplings (1, 2) are provided with external peripheral sealing elements (5, 6).

Description: METHOD FOR PRODUCING A VENTILATIONS DUCT SYSTEM Field of the Invention This invention relates to a method for producing a a ventilation duct system. Background of the Invention Conventional ventilation duct systems are composed of elongate straight parts and a large number of different connectors and end pieces, such as pipe bends, T-pieces, end outlets etc., which allow the ducts to be laid in forms deviating from the straight form. To make it possible to mount a ventilation duct system to suit its purpose, a great variety of connectors must be available. For example, pipe bends must be manufactured to have different angles, e.g. up to 90° in steps of 15°, which means that a very great number of variants must be manufactured in advance and stored, thus implying heavy capital expenditure for stock-keeping. Moreover, the finished connectors are relatively bulky to store and transport, which also results in high costs. An object of the invention is to provide a solution to these problems. US-A-2 392 220 discloses a store pipe PCT/SE94/00169 made up by sections connected by threads. Some of the sections are rolled or bent to a cylindrical configuration, SE-B-382 675 discloses 1 sealing rings on ducts. Summary of the Invention Said object is achieved by means of a method having the features defined in appended claim 1. Preferred embodiments of the invention are recited in the subclaims. According to one aspect of the invention, a kit comprises loose sleeve couplings and flat blanks which has been given such a shape and such dimensions that, after forming thereof and interconnecting its two opposite ends, it is connectable with said sleeve couplings by means of a peripheral joint, thereby forming an intermediate segment. The present invention brings the advantage that the number of standard products in stock is reduced since a limited amount of variants of sleeve couplings and intermediate segments can be combined to form many different connectors and end pieces. The sleeve couplings and flat elements included in the kit are made of metal sheet, preferably pregalvanised metal sheet when ventilation systems are involved. The flat elements are formed by bending or rolling, and their opposite ends are interconnected, preferably by welding. The formed elements are connected with the sleeve couplings and with each other preferably by means of folded seams. Their number is at least one and sufficiently many to form, together with the sleeve couplings, the connector, with no further deforming working thereof than the above-mentioned forming, preferably bending/rolling. A 90° pipe bend thus requires at least two sheet-metal elements. The cutting-out of flat sheet-metal elements from metal sheeting is advantageously carried out in such a manner that the cut-out sheet-metal elements supplement each other, which of course results in optimal utilisation of the metal sheeting. Some embodiments of the invention will now be described in more detail, reference being made to the accompanying schematic drawings. Brief Description of the Drawings Fig. 1 is a side view of two sleeve couplings and a top plan view of two flat elements; Fig. 2 is a side view of an assembled pipe bend with a 90° change of angle; Fig. 3 is a side view of two sleeve couplings and a top plan view of a flat element; Fig. 4 is a side view of an assembled pipe bend with a 60° change of angle; Fig. 5 is a side view of two sleeve couplings and a top plan view of a flat element; Fig. 6 is a side view of an assembled pipe bend with a 45° change of angle; Fig. 7 is a side view of two sleeve couplings and a top plan view of four flat elements; Fig. 8 is a side view of an assembled pipe bend, corresponding to the one shown in Fig. 2; Fig. 9 is a side view of two sleeve couplings of different sizes and a top plan view of a flat element; Fig. 10 is a side view of an assembled so-called reducer; Figs 11 and 12 illustrate a T-connector and a kit for producing the same; Figs 13-16 illustrate the connection between a sleeve coupling and an intermediate segment by means of a folded seam; Description of Preferred Embodiments Fig. 1 illustrates the components of a kit adapted to form a non-straight connector, in this case in the form of a pipe bend 24 for conducting a fluid, which is shown in Fig. 2. The separate components are two identical, substantially circular sheet-metal end sleeve couplings 1, 2 for connecting the pipe bend 24 with further fluid-conducting elements (not shown), and two flat blanks or sheet-metal elements 3, 4 supplementing one another. Each sleeve coupling 1, 2 has a first end 1c, 2c to be joined to corresponding ends or edges 3c, 4d of the blanks 3', 4' as bended, and a second end 1d, 2d for connection with said fluid-conducting elements. Each sleeve coupling end 1c, 1d, 2c, 2d has a smooth cylindrical shape and defines an opening in the associated sleeve coupling 1, 2. After the operations described in the Summary of the Invention, i.e., bending or rolling the blanks, and interconnecting the ends thereof, the blanks or sheet-metal elements are connectable with each other (at 3d, 4c) and with the circular sleeve couplings 1, 2 (at 1c, 3c and 2c, 4d, respectively) in the manner shown for delimiting a duct and, thus, for forming the pipe bend 24. Opposite ends 3a, 3b and 4a, 4b of the blanks 3, 4 are preferably welded together. The weld joints 3a, 3b and 4a, 4b are shown in Fig. 2. The pipe bend 24 has a change of angle from one sleeve coupling to the other, i.e. it forms an angle of 90°. All so-called segment angles are 15°. After forming and being connected by a folded seam, the two originally flat blanks 3, 4 form intermediate segments 3', 4' of the pipe bend 24. These cylindrical segments 3', 4' each have a central axis in the pipe bend 24. The sleeve couplings 1, 2 have central axes as well which in this pipe bend 24 form a predetermined angle of 90°. The sleeve couplings 1, 2 are each fitted with an external peripheral, elastic sealing ring 5, 6 which preferably is substantially U-shaped in cross-section, a so-called double lip seal, the web of which is fixed to the outside of the sleeve couplings 1, 2. The sealing rings 5, 6 establish a seal between the sleeve couplings 1, 2 and the above-mentioned further fluid-conducting elements. This type of seal and tubular connections generally are disclosed in US Patent 4,050,703 to Tuvesson et al. Fig. 3 illustrates the same end sleeve couplings 1, 2 and the same, originally flat blank 3, the components 1, 2, 3 producing the 60° pipe bend 7 illustrated in Fig. 4. It should be noted that also the flat blank 4 in Fig. 1 can be used to produce the 60° pipe bend in Fig. 4. The weld joint is then diametrically opposed to the joint shown in Fig. 4 (cf. Fig. 2). Fig. 5 illustrates end sleeve couplings 8, 9 which are of a slightly smaller height than the sleeve couplings 1, 2 and which are connectable with an originally flat (at 10) intermediate segment 10' for forming a 45° pipe bend 11 as shown in Fig. 6. The pipe bend 11 has 11.25° segment angles. Thus, the dimensions of the blank 10 are different from those of the blank 3 in Figs 1 and 3. Fig. 7 shows an alternative embodiment of the kit in Fig. 1 for producing a 90° pipe bend 16 as shown in Fig. 8. The components of the kit comprise two differently shaped end sleeve couplings 12, 13 and four flat blanks or sheet-metal elements 14, 3, 4, 15 which are connectable with each other to form intermediate segments 14', 3', 4', 15', and with the sleeve couplings 12, 13 to form the pipe bend 16. In this case, the sleeve couplings 12, 13 are not bevelled. To facilitate the connection with the sleeve couplings 12, 13, they are here provided with a collar 23. The blanks 3, 4 and the intermediate segments 3', 4' are identical with the blanks and the intermediate segments illustrated in Figs 1 and 2. Fig. 9 illustrates a kit for producing a connector 30 of decreasing cross-section, a so-called reducer that is illustrated in Fig. 10. To this end, the sleeve couplings 26, 27 are of different diameters, and the curvature of the flat element 28 (shown on a smaller scale) is adapted thereto. Figs 11 and 12 illustrate a T-connector 32, having two end sleeve couplings 35 secured to an intermediate segment 37' using a folding machine or other connection method known in the art. As in the other embodiments, the intermediate segment 37' is formed by shaping a blank 37, so that a third opening is provided for mating with the third or central sleeve coupling 33. Figs 13-16 show the folding operation which can be used to connect two separate components in the kit with each other. Fig. 13 illustrates the sleeve coupling 12 and the intermediate segment 14' formed to a circle, before being connected with one another. The edge portion of the intermediate segment 14' is bent outward by a folding machine (not shown) from the circumferential surface 25 of the pipe bend, essentially at right angles thereto, thereby forming a flange 22. The metal is not split during bending or folding because the deformation does not exceed the breaking strength of the material. The end of the sleeve coupling 12 facing away from the end supporting the seal 5 is now collared with the folding machine, but by means of other rollers which are arranged in a manner for forming the collar, if this has not been done before, cf. Fig. 7, for a folded seam connection with the intermediate segment 14'. The flange 22 is caused to engage that part of the collar 23 which extends substantially in parallel with the flange 22, cf. Fig. 14, by axial displacement of the segment 14' or the sleeve coupling 12. Subsequently, that part of the collar 23 which extends substantially at right angles to the flange 22 and around the same is bent in a folding machine using rollers and clamped against the flange 22 to form a reliable and tight peripheral joint. It will be appreciated that the folded seam connection may be "reversed", i.e. the collar is formed on the intermediate segment, while the sleeve coupling is formed with a radially projecting flange. The principles of the method of the invention are easily understood by the description above. The main steps are: determining a connection angle for the connector, shaping at least one flat blank to form a cylindrical element and joining the sleeve couplings to this element in the manner further specified in appended claim 1. General Advantages and Alternative Embodiments According to the invention, a number of advantages are obtained, some of which have been discussed in the introductory part of the specification. Further conventional connectors of the type disclosed can be hot-dip galvanised, which means that the peripheral groove in which the seal is to be arranged, must be formed before the hot-dip galvanising, since the zinc layer would otherwise crack and scale off in the area that is worked. Such hot-dip galvanising also results in the zinc layer partly filling the groove formed, thus reducing the space intended for the seal, which in turn causes problems when assembling the connector and a further pipe element. By means of the invention, these drawbacks are obviated, since the sleeve couplings can be manufactured of metal sheeting which is pregalvanised in a manner that allows working in the form of e.g. roll-forming of the groove. A further problem in conventional manufacture of connectors for ventilation duct systems is that in some cases the connector must be subjected to relative extensive working during the manufacture, in which the material hardens, implying that it will be difficult to form the groove in which the seal is to be arranged. During the forming, some portions of the groove frequently grow in an uncontrollable manner. Moreover, there is a risk that the material cracks in the transition zone between the groove and an adjoining straight part of the connector. Also this inconvenience will be obviated by means of the kit according to the invention, since the sleeve couplings included therein can be manufactured separately from a material which is easy to work and which requires neither e.g. pressure turning nor pressing, prior to the forming of the groove. The concept of the invention provides high flexibility since the sleeve couplings and blanks can be manufactured separately and, if suitable, in different factories. The blanks can be stored and transported in their flat state and then require but a small space, thus reducing the costs. The invention also creates the possibility of producing the finished products (pipe bends, T-pieces etc.) in connection with the site where the ventilation system is to be installed.

Claims: A method for producing a ventilation duct system comprising straight pipes and connectors therefore, said connectors comprising elbows, T-pieces and reducers, comprising the steps of: providing a number of cylindrical sleeve couplings (1) having a first sleeve coupling end (1c) and a second sleeve coupling end (1d), each said sleeve coupling end (1c, 1d) defining an opening in said cylindrical sleeve coupling (1), said first sleeve coupling end (1c) having a smooth cylindrical shape, and said second sleeve coupling end (1d) having an external peripheral elastic sealing ring and being matable with a straight pipe, said number comprising both similar sleeve couplings (1) and different sleeve couplings (1), the difference comprising the diameter and the angle of the plane containing said first sleeve coupling end (1c), selecting one pair of the cylindrical sleeve couplings from said number for each connector for the duct system, forming flat blanks (3') to cylindrical shapes and then joining the ends (3a, 3b)of the flat blanks (3'), thereby to provide cylindrical segments having a first segment end (3c) and a second segment end (3d), each said segment end (3c, 3d) having a smooth cylindrical shape and defining an opening in said cylindrical segment (3'), wherein the blanks having been given such a shape so as to, after said forming, alone or in combination with other flat blanks, define a connector intermediate, with the outermost first and second segment ends matable with a respective first sleeve coupling end of said pair of sleeve couplings; and, if said intermediate consists of a said combination of cylindrical segments, with the other segment ends matable with each other, joining said first sleeve coupling ends to said connector intermediate ends, and, if said intermediate consists a said combination of cylindrical segments, joining the other segment ends to each other, thereby to provide a connector, and joining the connectors to straight pipes. Method according to claim 1, wherein the connector is angled for enclosing a predetermined angle between straight pipes joined to its ends. Method according to claim 1, wherein one of said connectors is a 60° bend made up by two similar sleeve couplings and one segment, the first sleeve coupling ends bevelling 15°. Method according to claim 1, wherein one of said connectors is a 45° bend made up by two similar sleeve couplings and one segment, first sleeve coupling ends bevelling 11,5°. Method according to claim 1, wherein one of the connectors is a 90° bend made up by two similar sleeve couplings and two similar segments, the first sleeve coupling ends bevelling 15°. Method according to claim 1, wherein one of the connectors is a 90° bend made up by two unbevelled similar sleeve couplings and two different pairs of segments. Method according to claim 1, wherein one of said connectors is a 90° bend, made up by two similar sleeve couplings and two similar segments, the first sleeve coupling ends bevelling 15°. Method according to claim 1, wherein one of the connectors is a reducer made up by two sleeve couplings (26, 27)of different diameters and with unbevelled first ends. Method according to claim 1, wherein one of the connectors is a T-connector made up by two unbevelled similar sleeve couplings (35), a segment(37) having an opening connected to a central sleeve coupling (33). A method according to claim 9, wherein said external sealing ring is an elastomeric sealing element (5, 6). A method according to claim 10, wherein said sealing element (5, 6) is U-shaped and projects radially from said second sleeve coupling end. A method according to any one of claims 1-11, wherein at least one of said first and said second segment ends further comprises a radially projecting flange (22). A method according to claim 12, wherein said first sleeve coupling end (23) is adapted to be edge formed with said radially projecting flange (22). A method according to claim 13, wherein said first sleeve coupling end (23) is crimped over said radially projecting flange (22). A method according to any one of claims 1-11, wherein said first sleeve coupling end (1c, 2c) is adapted to be bonded to one of said first and second segment end (3c, 3d). A method according to claim 15, wherein said bonding includes folding or welding. A method according to any one of claims 1-16, where-in said flat blanks (3) are made of sheet metal.

Inventors: LENNARTSSON KENNETH, SONDEN CARL GUSTAF, LENNARTSSON, KENNETH, SONDEN, CARL GUSTAF, Sondén, Carl Gustaf 
Applicants: LINDAB AB
Application year: 1994
Main classification: F16L43
IPC codes: F16L13, F16L43, F16L41